wp_list_pages() │ WP 1.5.0

Keep in mind that ul tags will also be deleted and must be specified separately:

<ul>
	<?php wp_list_pages('title_li='); ?>
</ul>

Change the title to "Poetry", wrap it in the HTML tag <h2> and list only the permanent pages with IDs 9, 5 and 23:

<ul>
	<?php wp_list_pages( 'include=5,9,23&title_li=<h2>' . __('Poetry') . '</h2>' ); ?>
</ul>

Let's sort the list according to the ordinal numbers indicated on the "permanent pages" editing page:

<ul>
	<?php wp_list_pages('sort_column=menu_order'); ?>
</ul>

<ul>
  <?php wp_list_pages('sort_column=menu_order&title_li='); ?>
</ul>

Let's display the list sorted by date of creation of the "permanent page" and show the date next to each link:

<ul>
	<?php wp_list_pages('sort_column=post_date&show_date=created'); ?>
</ul>

Using the parameter exclude we will exclude pages with IDs 17,38:

<ul>
	<?php wp_list_pages('exclude=17,38' ); ?>
</ul>

Using the parameter include, create a list of only pages with IDs 35, 7, 26 and 13:

<ul>
	<?php wp_list_pages('include=7,13,26,35&title_li=<h2>' . __('Pages') . '</h2>' ); ?>
</ul>

Using the following example, you can display in the sidebar (or elsewhere) a list of child pages (subpages) of the permanent page you are currently on. To do this, use parameter child_of and check if there are any child pages for the current page (let's try to get child pages into variable $children, and if it works, let's output a list):

<?php
$children = wp_list_pages( 'title_li=&child_of=' . $post->ID . '&echo=0' );

if( $children ){
	?>
	<ul>
		<?php echo $children; ?>
	</ul>
	<?php
}
?>

Let's go further and display a list of child pages and make this list remain when we go to one of these child pages (i.e. for child pages, we get a list of single-level pages):

<?php
if( $post->post_parent ){
	$children = wp_list_pages( "title_li=&child_of=" . $post->post_parent . "&echo=0" );
}
else {
	$children = wp_list_pages( "title_li=&child_of=" . $post->ID . "&echo=0" );
}

if( $children ){
	?>
	<ul>
		<?php echo $children; ?>
	</ul>
	<?php
}
?>

An alternative version of the previous example.

This example can also be used in the sidebar, it will output:

• when you are on the home page, all of the top-level "permanent pages" will be shown;

• When you are on a top-level "permanent page" that has no child pages, all the same top-level "permanent pages" will be shown;

• When you are on a top-level "permanent page" that has child pages, those child pages and their child pages will be shown;

• when you are on a child page of the top-level "permanent page" (the second-level page), the child pages of the top-level "permanent page" (i.e., the child pages of the parent page) will be shown.

$output = wp_list_pages( 'echo=0&depth=1&title_li=<h2>Top level pages</h2>' );

if( is_page() ){
	$page = $post->ID;

	if( $post->post_parent ){
		$page = $post->post_parent;
	}

	$children = wp_list_pages( 'echo=0&child_of=' . $page . '&title_li=' );

	if( $children ){
		$output = wp_list_pages( 'echo=0&child_of=' . $page . '&title_li=<h2>Child Pages</h2>' );
	}
}

echo $output;

A list of child pages that will only be shown if the "permanent page" has child pages. The child pages will be shown both on the parent "permanent page" and on the child pages themselves. The difference from the previous example is that the name of the parent "permanent page" is in the header of the list:

<?php
if( $post->post_parent ){
	$children = wp_list_pages( "title_li=&child_of=" . $post->post_parent . "&echo=0" );
	$titlenamer = get_the_title( $post->post_parent );
}

else{
	$children = wp_list_pages( "title_li=&child_of=" . $post->ID . "&echo=0" );
	$titlenamer = get_the_title( $post->ID );
}

if( $children ){
	?>

	<h2> <?php echo $titlenamer; ?> </h2>
	<ul>
		<?php echo $children; ?>
	</ul>

	<?php
}
?>

This example shows how to get all child pages, on pages of any nesting level:

<?php
if( ! $post->post_parent ){
	// get child pages, for the "permanent page" of the top level
	$children = wp_list_pages( "title_li=&child_of=" . $post->ID . "&echo=0" );
}
else{
	// get the child pages if we are on the first level child page.
	//$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0");

	if( $post->ancestors ){
		// now get the ID of the very first page (the oldest one)
		// wp collects IDs in reverse order, so the "first" page will be the last
		$ancestors = end( $post->ancestors );
		$children = wp_list_pages( "title_li=&child_of=" . $ancestors . "&echo=0" );
		// that's it, now we will always have a list of all child pages,
		// whatever nesting level we are on.
	}
}

if( $children ){
	?>
	<ul>
		<?php echo $children; ?>
	</ul>
	<?php
}
?>

Since there is no way to tell wp_list_pages to output the tree (all nesting levels) of pages of a particular page (e.g. pages with ID 93), we can use get_pages() to do this trick:

<?php
// Use wp_list_pages to show the parent and all child pages
// (including all nested ones)
$pages = get_pages( 'child_of=93' );
$parent = 25;
if( $pages ){
	$pageids = [];

	foreach( $pages as $page ){
		$pageids[] = $page->ID;
	}

	wp_list_pages( [
		'title_li' => 'Parent page tree: ' . $parent,
		'include'  => $parent . ',' . implode( ',', $pageids ),
	] );
}
?>

By default, wp_list_pages() creates a list of this construction:

<li class="pagenav">Pages
	<ul>
		<li class="page_item page-item-4"></li>
		<li class="page_item page-item-5"></li>
		...
	</ul>
</li>

If we remove the title by putting an empty parameter title_li=, the view becomes like this:

<li class="page_item page-item-4"></li>
<li class="page_item page-item-5"></li>
...

Another way of putting it is this:

<li class="pagenav">
Pages [title_li]
  <ul>
	<!-- The list starts here if the 'title_li' parameter is blank -->
	<li class="page-item-2 page_item current_page_ancestor current_page_parent">
	  [parent of the current page]
		  <ul>
			<li class="page-item-21 page_item current_page_item">[current page]</li>
		  </ul>
	</li>
	<li class="page-item-3 page_item">[other pages]</li>
  </ul>
</li>

All li tags created with function wp_list_pages() are marked with CSS class page_item. When a page you are on appears in the list, another class current_page_parent is added to the li element of the list.

Thus, the list can be "colored" with the following CSS selectors:

.pagenav { ... } /* the main ul tag class that wraps the entire list */
.page-item-2 { ... } /* element related to page with ID 2 */
.page_item { ... } /* any list item */
.current_page_item { ... } /* current page */
.current_page_parent { ... } /* the parent page of the current page */
.current_page_ancestor { ... } /* any page either related to the current page (parent or daughter.) */

To achieve a global effect on list items, use the following selectors:

.pagenav  ul ul,
.pagenav .current_page_item ul ul,
.pagenav .current_page_ancestor ul ul,
.pagenav .current_page_ancestor .current_page_item ul ul,
.pagenav .current_page_ancestor .current_page_ancestor ul ul {
	display: none;
}

.pagenav .current_page_item ul,
.pagenav .current_page_ancestor ul,
.pagenav .current_page_ancestor .current_page_item ul,
.pagenav .current_page_ancestor .current_page_ancestor ul,
.pagenav .current_page_ancestor .current_page_ancestor .current_page_item ul,
.pagenav .current_page_ancestor .current_page_ancestor .current_page_ancestor ul {
	display: block;
}

<?php
// if it is a child page
if( $post->post_parent ){

	// collect related pages
	$relations = get_post_ancestors( $post->ID );

	// get child pages (if any)
	$result = $wpdb->get_results( "SELECT ID FROM wp_posts WHERE post_parent = $post->ID AND post_type='page'" );

	// if the child pages of this page turned out to be
	// get them merged with their relatives
	foreach( $result as $page_id ){
		$relations[] = $page_id->ID;
	}

	// add the current page to the related pages
	$relations[] = $post->ID;

	// make a comma-separated ID list of related, child and current
	$relations_string = implode( ",", $relations );

	// get the list using the include parameter
	$sidelinks = wp_list_pages( "title_li=&echo=0&include=" . $relations_string );
}
// if it is not a child page
else {
	// show only child pages one level
	$sidelinks = wp_list_pages( "title_li=&echo=0&depth=1&child_of=" . $post->ID );
}

if( $sidelinks ){
	?>
	<h2><?php the_title(); ?></h2>
	<ul>
		<?php // display links in <li> tags
		echo $sidelinks; ?>
	</ul>
	<?php
}
?>

If the site has an arbitrary record type with a tree structure, wp_list_pages() can be used to display such records as well.

In general, all of the above examples will work for this case as well, the only thing you need to change is the type of record the function will work with.

The record type is specified in the post_type parameter:

wp_list_pages( [
  'post_type'=>'portfolio',
  'title_li'=> __('Portfolio')
] );